Advanced Kinematic Tailoring for Morphing Aircraft Actuation

Abstract

Morphing aircraft concepts require powerful, compact, and lightweight actuators in order to realize the significant changes in the shape and aerodynamics desired. One source of inefficiency and lost performance common to all types of actuators is the mismatch between the force-versus-stroke profile available from the actuator and that required by the load. This work investigates a novel spiral spooling pulley mechanism that allows for kinematic tailoring of the actuator force profile to better match the force required to drive a given load. To show the impact of kinematic tailoring on actuator efficiency, a representative case study is made of a pneumatic artificial muscle-driven morphing camber airfoil employing the fish bone active camber concept. By using an advanced spiral pulley kinematic mechanism, the actuator force profile is successfully tailored to match the morphing actuation torque required, with an additional torque margin added to account for any unmodeled effects. Genetic algorithm optimization is used to select the geometric parameters of the spiral pulley that maximize the energy efficiency of the actuator while ensuring it is able to produce the required torque levels. The performance of the optimized spiral pulley is compared to a baseline case employing an optimized circular pulley, which does not alter the shape of the actuator force profile, to show the performance improvement provided by the kinematic tailoring.